Conventionally, onboard devices locking and unlocking a vehicle door based on wireless communication with a portable device are known. For example, when a user possessing the portable device grips a door handle, when an operator provided in a vicinity of the door handle is operated, or the like, the onboard device performs wireless communication with the portable device and unlocks/locks the vehicle door.
According to Patent Literature 1, a method is disclosed in which, when a first switch provided to a particular vehicle door is operated, an authentication is performed via wireless communication between the portable device and the onboard device, and when the authentication is performed properly, the particular vehicle door is unlocked. In addition, according to a method described in Patent Literature 1, in a state where the particular vehicle door is unlocked by the first switch operation, all vehicle doors are unlocked when a second switch provided to the particular vehicle door is operated. Therefore, in the method described in Patent Literature 1, all the vehicle doors are not unlocked unless the second switch is operated after unlocking the particular vehicle door. Accordingly, the method can prevent a third party from entering the vehicle due to unintentional unlocking of the vehicle doors and safety of an occupant can be enhanced when aboard the vehicle.
In addition, an onboard device is becoming popular which locks the vehicle doors when the vehicle travels at or exceeds a specified speed. Such onboard devices can prevent the occupant in the vehicle from accidentally opening the vehicle door during travel and secure the safety of the occupant while the vehicle is in motion.